SB13U1 - Test - The Characteristics of Life

SB13U1 Study Notes for Unit I Test The Characteristics of Life ● ● The characteristics of life are the same for all living things, whether they are small, simple, or large, complex. ○ Cell theory states that: 1. Living things are unicellular or multicellular 2. All cells come from pre-existing cells 3. The cell is the basic unit of life ○ Cells can come in two categories: 1. Eukaryotes: uni/multicellular organism that contains membrane-bound organelles 2. Prokaryotes: unicellular organism that does not contain membrane-bound organelles Everything that is alive reproduces. The primary goal of reproduction is to have children in order to maintain genetic diversity from generation to generation. Two main types of reproduction: 1. Sexual: involves a sperm and egg; follows the process of meiosis 2. Asexual: involves a single parent cell; follows the process of mitosis All living things move Locomotion:movement that free-moving organisms exhibit Growth Movement: movement that non-free-moving organisms exhibit 1. Magic Growth Movement: non-directional responses to stimuli (e.g. mimosas, lungworts, etc.) 2. Tropic Growth Movement: directional responses to stimuli (e.g. vines, pinto beans, etc.) ● All living things acquire and use energy ○ Acquiring energy can be done in two major ways 1. Autotrophically: organisms make their own glucose through the process of photosynthesis (use chlorophyll and sunlight) 2. Heterotrophically: organisms cannot make their own glucose so consume other living and dead organisms ○ Using energy can be done through chemical reactions within an organism’s body Metabolism: the sum of these chemical reactions divided into two branches) 1. Anabolism: the building up of large/complex molecules from small/simple ones 2. Catabolism: the breakdown of large/complex molecules into small/simple ones ● All living things grow and develop ○ ○ Unicellular organisms increase the volume of their cytoplasm, which involves gaining more cytosol (liquid), and creating more organelles (the machinery of cell) Multicellular organisms undergo cell division and specialization All living things have levels or classification Highly organized from the smallest part to the largest part which allows structures at every level to perform specific functions Atom Molecule Macromolecule Organelle Cell Tissue Organ Organ system Organism All living things have genetic information Genetic info comes in the form of a molecule called DNA ( ● ● ● ● ● ● ● ● ● All living things respond to their environment ○ Stimuli: changes that living things respond to; may be in their internal or external environments ○ Homeostasis: a constant internal state All living things adapt and evolve British naturalist Charles Darwin came up with a mechanism for evolution called natural selection Biodiversity The variety and number of different species on our planet Species: all organisms capable of breeding freely with each other under natural conditions Three types of biodiversity 1. Genetic Diversity: genetic variability among organisms in a single species 2. Species Diversity: the quantity and variety of species present 3. Structural Diversity: the range of physical shapes/sizes within an ecosystem Interactions between Species Food supply (e.g. bone worms feed on bones of dead whales) Protection (e.g. certain species of ants live within the trunks of Cecropia trees Transportation (e.g. many seeds have hooks that they can stick to passing animals) Reproduction (e.g. many bird species build nests in abandoned tree cavities made by woodpeckers for their own nests) ● ● Hygiene (e.g. large fish have external parasites removed by small fish/shrimp) Digestion (e.g. bacteria live in the large intestine of humans and produce vitamins) Deoxyribonucleic acid) Viruses contain genetic info in the form of DNA or RNA (in retroviruses) Taxonomy ● ● ● ● ● ● ● ● The branch of biology that classifies organisms and assigns each a universally-accepted name Taxon: a category used to classify organisms (plural: taxa) Modern taxonomy is based on ○ Embryological similarities ○ Biochemical similarities ○ Genetic similarities ○ Cellular organization ○ Evolutionary relationships ○ Morphology Classification/scientific study of the forms and structures organisms have Three important structures within organisms 1. Homologous Structures: organisms share same structure but different functions (e.g. wing of a bird and human forearm) 2. Analogous Structures: organisms share similar functions but different structures (e.g. wings of a bird and a butterfly) 3. Vestigial Structures: some organisms contain non-/slightly functioning features that seem to be left over from previous ancestor (e.g. “hips” in snakes and human appendix) Carolus Linnaeus (1707–1778) Set up a classification system based on structural similarity Developed the naming system Binomial Nomenclature ○ The system of assigning a specific name consisting of two parts – the genus name and the species name ○ Genus name is always capitalized and species name is never ○ All names are in Latin (understood by all scientists) ○ All names either italicized or underlined Created seven levels of classification 1. Kingdom2. Phylum 3. Class 4. Order 5. Family 6. Genus 7. Species *Recently, scientists have added another level above Kingdom – Domain Phylogeny The evolutionary history of an organism Phylogenetic Trees: scientists depict these diagrams that show the evolutionary relationships between different groups/species of organisms Clade: taxonomic group that includes a common ancestor and its descendants Cladistics ● ● ● Based on the presence or absence of recently evolved traits, a technique for establishing evolutionary relationships (e.g. feather of birds; only birds have feathers) Use features called “shared derived characters” which are features that evolved only within the groups; these are strong evidence of common ancestry Cladogram: diagram that shows the evolutionary relationships among a group of organisms Dichotomous Key A series of branching, two-part statements used to identify organisms Kingdoms and Domains ● ● ● Kingdoms are the highest level of biological hierarchy Domains are super kingdoms – a taxonomic level even higher than kingdoms 1996, Carl Woese founded the 3 Domains of Life 1. Domain Eubacteria Kingdom Eubacteria 2. Domain Archaea Kingdom Archaea 3. Domain Eukaryotes ● ● ● ● Kingdom Animalia Kingdom Plantae Kingdom Fungi Kingdom Protista The six-kingdom/three-domain system is based on phylogenetic relationships revealed by genetic evidence The Domain Archaea ● ● ● Cell membranes/walls have a unique chemical makeup and most lack peptidoglycan Cell membranes/walls are very resistant to physical/chemical disruptions Many inhibit extreme environments Methanogens: live in low-oxygen environments (e.g. swamps, lakes, marshes, sewage lagoons, digestive tracts of some mammals, etc.) Halophiles:live in highly saline environments(e.g.theDeadSea,foods preserved by salting, etc.) Extreme Thermophiles: live in extremely hot environments (e.g. hot springs, hydrothermal vents on ocean floor, etc.) Psychrophiles: live in extremely cold environments (e.g. Antarctic and Arctic Oceans, cold ocean depths, etc.) The Domain Eubacteria Characteristics ● ● ● ● ● ● ● ● ● ● ● ● Found in all types of environment Largely responsible for: Properties of atmosphere Properties of soil Web life on Earth (producers and decomposers) Biogeochemical cycles Prokaryotic Complex cell walls composed primarily of peptidoglycan ○ Peptidoglycan: large molecule that forms long chains and gives bacteria resistance and protection ○ Dr. Hans Christian Gram (Danish physician) grouped bacteria into: 1. Gram-Positive Bacteria: bacteria that have a strong and rigid cell wall that does not react with a purple Gram stain 2. Gram-Negative Bacteria: bacteria that have a fragile cell wall with an extra protein layer which does not react with purple Gram stain) May be surrounded by a sticky capsule ○ Capsule: outer layer that provides some protection for the cell against environmental changes and infectious viruses ○ Thickness of capsule is indication of the virulence (strength) of the species Chromosome is single loop of DNA found in nucleoid Ribosomes are scattered throughout cytoplasm One or more flagella (singular: flagellum) Flagellum: whip-like structure that enables them to swim/move Many pili (singular: pilus) Pilus: small, hair-like structure made of stiff proteins that allows cells to attach to other cells/surfaces One or more plasmid Plasmid: small loop of DNA that carries a small number of genes Come in a variety of shapes and sizes ○ Coccus (plural: cocci): round-shaped bacterial cell (e.g. strep throat, etc.) ○ Bacillus (plural: bacilli): rod-shaped bacterial cell (e.g. tuberculosis, etc.) ○ Spirillum (plural: spirelli): spiral-/corkscrew-shaped bacterial cell (e.g.cholera and syphilis) Come in particular arrangements Diplo: in pairs Staphylo: in clumps Strepto: in strings Classification and Phylogeny More than 12 separate groups but 6 main ones ● ● ● ● ● Proteobacteria (purple bacteria): some photosynthesis differs from plants; responsible for diseases like gonorrhea and dysentery Green Bacteria: found in salt-water environments and hot springs Cyanobacteria (blue-green algae): photosynthesis is similar to plants;form symbiotic relationships with fungi Gram-positive Bacteria: cause strep throat and bacterial pneumonia Spirochetes: move with a corkscrew motion; cause syphilis ● ● ● ● ● Chlamydias: parasites that live within other cells; cause chlamydia (most common STD) Metabolism Autotrophic bacteria make their own food by assembling complex carbon molecules from simple inorganic chemicals Inorganic Chemicals: chemical produced by abiotic thing (e.g. water) Heterotrophic bacteria get their nutrients from carbon containing organic chemicals found in other living/dead organisms Organic Chemicals: chemical produced by biotic things (not CO2) Aerobic Respiration: process that takes place in the presence of oxygen ○ Obligate Aerobe: an organism that cannot survive without oxygen (e.g. bacteria that is responsible for tuberculosis, pneumonia, etc.) ○ Facultative Aerobe: an organism that prefers to function in the absence of oxygen but when necessary, can function with oxygen Anaerobic Respiration: process that takes place in the absence of oxygen ○ Obligate Anaerobe: an organism that cannot survive in the presence of oxygen (e.g. bacteria responsible for lactic acid and alcoholic fermentation,tetanus, etc.) ○ Facultative Anaerobe: an organism that prefers to function in the presence of oxygen but when necessary, can function without oxygen for a limited period of time (e.g. e-coli in the human intestines) Reproduction ● ● ● ● ● Asexually by binary fission ○ Binary Fission: the division of one parent cell into two genetically identical daughter cells ○ Bacterial haploid chromosome and the plasmid replicate ○ Bacterial cell elongates and mesosome forms new cell wall through the midsection of elongated bacterial cell ○ When new cell wall is fully formed, the elongated cell splits forming two new daughter cells (identical to original bacterial cell) Whole process could take 20–30 minutes – very high rate of reproduction Bacteria increase their genetic info by these processes: ○ Conjugation: process in which DNA parts (fertility factor: when plasmid is donated to another bacteria) are transferred from one bacteria to another through sexual pilus ○ Transformation: process in which a bacterial cell takes in and uses pieces of DNA from a dead bacteria of same species ○ Horizontal Gene Transfer: process in which DNA fragments are taken from a different species of bacteria ○ Transduction: process in which a virus transfers DNA from one bacterium to another Strategy for surviving unfavorable conditions is bacterial sporulation Method in which bacteria produce endospores to survive harsh environments/periods Endospore: highly resistant structure that forms inside certain bacteria in response to stress; protects cell’s chromosome from damage; can remain dormant (inactive) for many years Bacterial Diseases ○ Bacteria are responsible for many diseases (e.g. from minor ear infection to the bubonic plague) ○ ● Some bacteria cause diseases by producing and releasing toxins (e.g. botulism food poisoning caused by toxin bacterium Clostridium botulinum released) ○ Some bacteria contain toxins that aren’t released until they die (e.g. E.coli) Antibiotics and Antibiotic Resistance ○ Competition between prokaryotes and fungi result in antibiotic substances Antibiotic: substance that can kill or weaken microorganisms ○ Overuse of antibiotics can cause bacteria to adapt and become resistant so that antibiotics are no longer effective Viruses ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● Small, non-living, infectious particles consisting of either DNA or RNA surrounded by a protein capsule (called a capsid) which can take on various geometric shapes Do not have key characteristics of living cells however they can reproduce but without a host cell) Virus means “poison” in Latin Spread easily from host to host (of same species) Sometimes cause epidemic (particular region) or pandemic (global) infections because they are interspecies viruses Classified based on size, shape, type of genetic material, etc. Have spikes for landing on host cell Bacteriophage: virus that infects bacterial cells; injects DNA into bacterium but capsid remains outside cell unlike other viruses; have complex head/tail structure Viral Diseases are caused ○ Some are key in ecosystems because they control the populations of other organisms ○ Responsible for many human/animal/plant diseases Human – common cold, smallpox, chicken pox, measles, polio, HIV/AIDS, etc. Animal – mad cow disease [see Prions] Plant – Tobacco Mosaic Virus [see Viroids] Uses of viruses in biotechnology: ○ Vaccines: prevent spreading of infectious diseases ○ Bacteriophages: to kill pathogenic bacteria (lytic cycle) ○ Gene Therapy: for fixing or replacing defective genes using the viruses as vectors Vector: carrier of genetic material ○ Drug Delivery: using viral capsules to deliver medicine to target tissues/organs Vaccinations: mixtures that contain weakened forms/parts of a virus ○ Administered by injection which triggers a response by the immune system without causing an infection ○ Immune cells have a chemical memory of the virus and kill it by replicationViroids Small, infectious pieces of RNA responsible for some serious plant diseases Smaller than any virus and do not have capsids Their RNA does not code for any proteins Plant pathogens (disease-causing agent) that can quickly destroy crop plantsPrions Infectious protein particles that cause some serious diseases in mammals (especially in the brain and nervous tissue) Brains of affected mammals are full of spongy holes ● Cattle suffered from mad-cow disease and humans who ate the contaminated meat developed a new human disease: Creutzfeldt Jakob Disease Important People ● ● ● ● ● ● Edward Jenner: English doctor who discovered the first vaccine – for smallpox Jonas Salk: developed the vaccine for polio (1955) Dmitri Iwanovsky: identified and isolated the firs plant virus – Tobacco Mosaic Virus Kingdom Protista Play key roles in aquatic ecosystems The ones that perform photosynthesis are some of the major producers in the oceans Non-photosynthetic ones are important consumers, especially at microscopic level They dominate the lowest levels of most aquatic food pyramids ● ● ● Abundant in moist terrestrial environments including soil Cause some important diseases in humans/animals/plants ○ Very serious diseases: Malaria (caused by Plasmodium), sleeping sickness, etc. ○ Less serious diseases: giardiasis/”beaver fever” (caused by Giardia lamblia) Some are valuable to humans Porphyra is in seaweed (nori) used to wrap sushi rolls Other products made from seaweed are: agar and carrageenan (used as food additives), toothpastes, cosmetics, paints, etc. ● ● ● ● ● ● Exhibit a variety of cell features, different ways of moving (if at all), different ways of getting nutrients/energy, and different ways of reproducing Most diverse kingdom of eukaryotes “Catch-all” for any species that do not fit in any other major kingdoms of life Cannot be classified into clades Seven representative groups ○ Euglenoids: autotrophs and photosynthetic; usually have two flagella ○ Ciliates: heterotrophs; many cilia but no cell walls Cilia (singular: cilium): hair-like structures that provide movement ○ Diatoms:autotrophs and photosynthetic;covered by silica shells ○ Slime Molds: heterotrophs; life cycles have unicellular and multicellular stages ○ Red Algae: autotrophs and photosynthetic; no cilia or flagella; cell walls made of cellulose The Origins of Eukaryotes ○ Protists were the first eukaryotes – cells have nucleus/ membrane-bound organelles ○ ● ● ● ● ● ● Internal organelles probably developed when the cell membrane of a prokaryotic ancestor – a bacterium or archaea – folded in half ○ Mitochondria and chloroplasts are two organelles that have particularly interesting origins are present-day Many similarities and are thought to have originated by endosymbiosis (the relationship in which one type of cell lives within another type of cell) Life Cycles of Protists ○ Reproduce sexually and asexually ○ Haploid: cell containing half the usual complement of chromosomes (n) ○ Diploid: cell containing two copies of each chromosome (2n) ○ Zygote: cell formed by the fusion of two sex cells; is diploid AlternationofGenerations:lifecycleinwhichdiploidindividualproducessporesthat create haploid individuals; the haploid individuals reproduce sexually, producing sporophyte individuals and completing the cycle Sporophyte: diploid organism that produces haploid spores in an alternation of generations life cycle Spore: haploid reproductive structure; capable of growing into a new individual Gametophyte: haploid organism that produces haploid sex cells in an alternation of generations life cycle Life cycle of a Plasmodium (protist that causes malaria) consists of six steps1. Plasmodium zygotes pass through the gut way and develop in oocysts which produce many haploid sporozoites by meiosis and then travel to a mosquito’s salivary glands 2. When the infected mosquito bites a human, it injects sporozoites into the blood which carries them to liver cells 3. Sporozoites reproduce asexually in liver cells producing many merozoites 4. Merozoites enter bloodstream, invade red blood cells, and reproduce asexually and when red blood cells die, merozoites are released causing fever and chills 5. Some merozoites in red blood cells develop into immature male/female gamete cells which are released into the bloodstream 6. Female mosquito ingests blood from infected human and the gamete cells in the blood mature in her gut and fuse by two to form zygotes Kingdom Fungi ● Important in ecosystems, economy, and health ○ Ecosystems: decomposers (food chains and nutrient cycles); symbiotic relationships with plants (glomeromycetes and with bacteria – lichens) ○ Economy: food industry and alcohol industry; pharmaceutical industry (antibiotics and immunity reductors) ○ Health: many cause diseases in animals and insects; some are invasive ● ● ● ● ● ● ● Eukaryotic, multicellular organisms, approximately 100 000 species Approximately 400 million years old (have their own clade) Closer related to animals than plants Include mushroom, molds, and yeasts Have complex life cycles (sexual and asexual stages) ○ Form zygotes that produce haploid spores ○ Meiosis: form of cell division in which a single cells produces four haploid daughter cells Structure consists of a mycelium ○ Mycelium: a branched mass of hyphae Forms the body of fungi below ground Hyphae grows at tips and as it grows, nuclei multiply by mitosis ○ Hyphae: thin filament that makes up the body of a fungus; consist of long tubes of cytoplasm containing many nuclei ○ Chitin: complex poly saccharide chemical found in the cell walls of fungi Symbiotic relationship is lichens (combo of photosynthetic green algae and fungi) ○ Fungi’s mycelium envelops and protects green algae and supplies them with water and minerals ○ In return, green algae supplies fungi with food Kingdom Plantae Developed root system Developed cuticle layers Cuticle: waterproof, waxy coating Developed stomata Stomata: small opening in the epidermis that allows gas exchange Developed complex chloroplasts and cell walls composed of cellulose and lignin fibers Includes many subsections ● ● ● Bryophytes (the mosses) Lycophytes/Pteridophytes (the ferns) Gymnosperms/Angiosperms (the seed plants) More than 270 000 species known Approximately 500 million years old Thought to have evolved from charophyte Charophyte: early green algae of the kingdom Protista Can survive in many different climatic conditions Important in ecosystems ● ● ● ● Diversity of life on planet Food web producers Shelter for other forms of life Nutrient cycles (carbon dioxide/oxygen balance in atmosphere) ● Symbiotic relationships with many other forms of lifeImportant in economy ○ Food and beverage industry ○ Pharmaceutical industry ○ Construction and forestry ○ Horticulture ○ Agriculture ○ BiofuelsMany are endangered and at risk due to habitat destruction, pollution, invasive species, climate change, etc. (77 of Ontario’s native plants at risk) Complex life cycles, both asexual (mitosis) and sexual (meiosis) reproduction Called an alternation of generations life cycle with diploid and haploid states generation produces spores Diploid Haploid generation produces gametes (sex cells) Adaptation to life on land Kingdom Animalia ● ● Most evolved and complex multicellular, eukaryotic organisms Approximately 700 Million Years Old Common ancestor: colonial choanoflagellate protists Bilateral symmetry: symmetry around a midline Further divided into two main branches 1. Protostomes: during embryonic development, mouth forms before anus 2. Deuterostome: during embryonic development, anus forms before mouth ● Cell specialization (e.g. nerve cells form to create nervous system) ● Body Segmentation(body cavities) ● Embryonic development (3 germ layers) Germs layers: layers that form during early embryonic development and give rise to specialized tissues ○ Ectoderm (gives rise to skin and nervous system) ○ Endoderm (forms inner lining of the gut and in some organisms, the respiratory system) ○ Mesoderm (gives rise to the circulatory, reproductive, excretory, and muscular systems) ● Includes invertebrates and vertebrates ○ Invertebrates: animal that does not have a backbone (e.g. insects, worms, rotifers, etc.) ○ Vertebrates:animals with backbone/notochord(e.g.fish,amphibians,reptiles,birds,and mammals)